import Vue from 'vue'

Vue.directive('tableScroll', {
  bind (el, binding) {
    // el-table 内容滚动区域
    const bodyWrap = el.querySelector('.el-table__body-wrapper')
    bodyWrap.addEventListener('scroll', function () {
      let sign = 0
      // 滚动到底部
      const scrollDistance = this.scrollHeight - this.scrollTop - this.clientHeight
      if (scrollDistance <= sign) {
        binding.value()
      }
    })
  }
})

// el-select 下拉指令
Vue.directive('selectScroll', {
  bind (el, binding) {
    // 获取滚动页面DOM
    let dropdownWrap = el.querySelector('.el-select-dropdown .el-select-dropdown__wrap')
    let scrollPosition = 0
    dropdownWrap.addEventListener('scroll', function () {
      // 当前的滚动位置 减去  上一次的滚动位置
      // 如果为true则代表向上滚动，false代表向下滚动
      let flagToDirection = this.scrollTop - scrollPosition > 0
      // console.log(flagToDirection ? '滚动方向：下' : '滚动方向：上')

      // 记录当前的滚动位置
      scrollPosition = this.scrollTop

      // 记录滚动位置距离底部的位置,在滚动位置距离滚动页面底部一定高度时在触发，例如距页面底部只有100px时触发handleScroll事件
      const LIMIT_BOTTOM = 10
      let scrollBottom = this.scrollHeight - (this.scrollTop + this.clientHeight) < LIMIT_BOTTOM
      // 如果已达到指定位置则触发
      // 如果向下滚动 并且距离底部只有10px
      if (flagToDirection && scrollBottom) {
        // 将滚动行为告诉组件
        binding.value(flagToDirection)
      }
      // 如果是向上滚动  并且距离顶部只有100px
      if (!flagToDirection && this.scrollTop < LIMIT_BOTTOM) {
        binding.value(flagToDirection)
      }
    })
  }
})

// v-dialogDrag: 弹窗拖拽
Vue.directive('dialogDrag', {
  bind (el, binding, vnode, oldVnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header')
    const dragDom = el.querySelector('.el-dialog')
    dialogHeaderEl.style.cursor = 'move'

    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const sty = dragDom.currentStyle || window.getComputedStyle(dragDom, null)

    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop

      // 获取到的值带px 正则匹配替换
      let styL, styT

      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (sty.left.includes('%')) {
        styL = +document.body.clientWidth * (+sty.left.replace(/\%/g, '') / 100)
        styT = +document.body.clientHeight * (+sty.top.replace(/\%/g, '') / 100)
      } else {
        styL = +sty.left.replace(/\px/g, '')
        styT = +sty.top.replace(/\px/g, '')
      }

      document.onmousemove = function (e) {
        // 通过事件委托，计算移动的距离
        const l = e.clientX - disX
        const t = e.clientY - disY

        // 移动当前元素
        dragDom.style.left = `${l + styL}px`
        dragDom.style.top = `${t + styT}px`

        // 将此时的位置传出去
        // binding.value({x:e.pageX,y:e.pageY})
      }

      document.onmouseup = function (e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})

// v-dialogDragWidth: 弹窗宽度拖大 拖小
Vue.directive('dialogDragWidth', {
  bind (el, binding, vnode, oldVnode) {
    const dragDom = binding.value.$el.querySelector('.el-dialog')

    el.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - el.offsetLeft

      document.onmousemove = function (e) {
        e.preventDefault() // 移动时禁用默认事件

        // 通过事件委托，计算移动的距离
        const l = e.clientX - disX
        dragDom.style.width = `${l}px`
      }

      document.onmouseup = function (e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})

Vue.directive('move', {
  inserted: function (el) {
    const dragDom = el.querySelector('.move')
    dragDom.style.cursor = 'move'
    dragDom.onmousedown = (e) => {
      event.stopPropagation()
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - el.offsetLeft
      const disY = e.clientY - el.offsetTop
      document.onmousemove = (e) => {
        // 用鼠标的位置减去鼠标相对元素的位置，得到元素的位置
        let left = e.clientX - disX
        let top = e.clientY - disY
        // 移动当前元素
        el.style.left = left + 'px'
        el.style.top = top + 'px'
      }
      document.onmouseup = (e) => {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})
